Fluid circulation system



April 1939. M. P. PARCARO FLUID CIRCULATION SYSTEM Filed March 31, 1936p W a B. W w/u F a a 40 W w m m g 5 9 m 6 lllil M w 8 2 w 5 y w 5 I L INV EN TOR. M/CH/IEL R PARC/720 ATTORNEY.

Patented Apr. 1939 umreo'srArr-zs PATENT OFFICE Newark, N. 1., acorporation of Delaware tlon,

Application March :1, 1930, Serial No. use:

1 Claims. (01. 02- 15) This invention relates to fluid circulation, andmore particularly to the .flow of fluid through refrigerating systems.

The general object of the invention is to provide an improved method ofand means for controlling the capacity of fluid compressors.

Another object of the invention is to provide for the reduction of thecapacity of a compressor in such manner that the power input to thecompressor is correspondingly reduced. In the past, various devices andmethods have been devised for reducing compressor capacity. However,they have quite generally proven unsatisfactory, either because-of highcost, me liability, or the setting up of ineflicient operatingconditions. 5

It is another object oi the invention to provider a system of compressorcapacity control which is inexpensive and reliable, and which results ineflicient operating aonditions, thus overcoming the shortcomings ofdevices heretofore known.

It is another object of the invention to provide a system of compressorcapacity control which may be applied to the various cylinders of a'multi-cylinder compressor and/or to a plurality of compressors operatingin parallel arrangement. A feature of the invention resides in reducinthe capacity of a multicylinder compressorby recirculating throughthecompressor gas pass ing from one or more cylinders of the compressor,while gas passing from the remaining cylinder or cylinders is disposedof in the normal way. The cylinders or compressors from which gas isrecirculated cease to deliver high pressure gas to the dischargereservoir of the apparatus, but

deliver gas at the suction pressure of the apparatus. 'I'hese'cylinders,therefore, do no work of compression. Accordingly, the power consumptionof the entire apparatus varies very functioning in the normal way. Thus,for example, if one cylinder of a two cylinder conipressor is cut out ofservice (that is, if fluid from. one cylinder is recirculated throughthe com-. pressor), the power necessary'to drive'the compressor willapproximate one-half of the power required when both of the cylindersare operating in the normal manner.

Another feature of the invention resides in 50.the provision of meansfor preventing the recirculation to the compressor intake of. highpressure gas delivered by a cylinder operating in the normal way, whilelowpressure gas delivered by another cylinder is returned to thecompressor intake. r a

e vi

A invention; and

:from cylinder 1 to line H, but does not permit flow in a reversedirection.

nearly in proportion to the number ot cylinders Another feature oi 'theinvention resides in automatically controlling the reduction of thecapacity of a compressor.- The control means may operate responsive tovariations in the pressure or temperature or fluid supplied to the com-6 pressor, or in any other suitable manner.

' Other'objects, features and advantages of the invention will be moreapparent from the following description to be read in connection withthe accompanying drawing in which: m

Fig. 1 illustrates a mechanical refrigeration system embodying theinvention; V

Fig. 2 illustrates a modification of the invention; 7 r

Fig, 3 illustrates a further modification of the M Fig. 4 illustrates amodified ement of the invention.

. Referring now to the drawing, 5 designates a compressor havingcylinders 6 and i. A suction line 8 provides communication between thecompressor 5 and the evaporator 16 of a refrigeration system includingthe compressor 5, condenser I7 and expansion valve. It. Fluid passingfrom cylinder 6 flows through pipe 9, and 25 fluid passing from cylinderlilows through pipe l0. Pipes S'and I0 communicate with'line ii, leadingto the condenser H. A bypass line I! connects pipe l0 and suction line8. Bypass line I! is provided with a valve l3. Pipe III is provided witha check valve ll, disposed beyond the connection of bypass line I! inthe line of normal fluid flow.- Check valve ll permits fluid to passUnder normal ioad'conditions, suction gas passes into cylinders! and Ithrough suction line 8 and is discharged alternately into. dischargelines 9 and II, whence it passes to the condenser l1 through .line II.Under such conditions stop valve II in bypass line I2 is closed; checkvalve I! offers no appreciable resistance to' flow of gas through pipeII to line II; and.

the operation'of the apparatus is thatoi a conventional two-cylindercompressor.

. When the load on the refrigerating system is reduced,"thef gaspressure in suction-line I ialls. When the pressure has reached apredetermined low point, pressurestat ii in suction line I causes valveIt to thus providing a free path for the gas discharged by eachcompression stroke of cylinder I to return .to suction line 8. Checkvalve 14, by its self closing action, prevents high pressure gas fromdischarge lines 9 and II from entering bypass line It. 55

Under low-load operating conditions, only cylinder 6 compresses gas fromthe suction presplaced at approximately the suction pressure prevailingin suction line 8. The cylinder 1 does practically no compression andtherefore requires practically no power for its operation. Thus, whilethe capacity of the compression apparatus has been reduced by one-half,the

power input has also been reduced to approximately the same extent, orin direct proportion to the reduction in compressor capacity.

It will be observed that the recirculated gas is supplied to the-feedline'which. serves both of the cylindersof the compressor. same gas isnot continuously recirculated, as would be they case if the gasdischarged from a cylinder were re-supplied' to that cylinder only.

Accordingly, excessive heating of the compressor,

which would result'irom the continuous recirculation of the same gas, isavoided.

Although valve 83' is illustrated and described as being under thecontrol of pressurestat .li, applicant does not restrict himself to thistype of control. Valve I! may be controlled manually, by a thermostatresponsive to the suction temperature oi the fluid to be compressed, bya thermostat responsive to temperatures created by the evaporator II, orin any manner. d

Although this description has been directed to a two cylindercompressor, it is to be understood that the invention may be-used inconnection with a compressor having three, or more cylinother suitableders. In such 'case, two or more bypass lines 12' wouldbe used, thevalves in the difierent bypass lines .operating successively tounloaddiiterent cylinders of the compressor. Such an arrange! ment isillustrated in Fig. 4, m which a third cylinder designated la, isprovided. Cylinder "la is provided with a discharge line "a, bypass linel2a,valve "a and mock valve a, respectively similar to the elements II,II, II and II associated with cylinder 1. The valves I! and lac operatesuccessively, so that under different operating conditions differentnumbers of the cylinders will be functioning in the normaimanner.Irrespective of the number cylinders.

the power input to the compressor will vary approximately in proportionto the actual work of compression done by-the active cylinders. Ii. itis desired to completely unload the compressor without interrupting theoperation pr the compressor driving means, each cylinder of thecompressor may have a by-pass line associated therewith,

By the provision of by-pass lines and valves corresponding to elementsl2, II and l4,the "capacity of compressor apparatus comprising two .ormore compressors operating in. parallel arrangeinent may be varied inaccordance with load requirements. v L

In the modification of the invention illustrated in Fig. 2, valves=13and 14 are replaced by a three way valve 2|). Valve 20' is controlled byinstrument I! in substantially the same wafythat valveii of Fig. l iscontrolled.by instrument Ii. Valve inder 1 into pipe I! or into pipe [0.When the valve delivers fluid from cylinder I to pipe 12, it

Thus the and H from entering into pipe l2. When valve 20 delivers fluidfrom cylinder 1 to pipes in and i i, it effectively prevents flowthrough pipe l2.

In operating air conditioning systems, it is sometimes desirable to coolor to cool and dehumidity air and then to reheat the air-beforesupplying it to the enclosure served by the system. Such operation isfrequently adopted where precise control of relative humidity isimportant. In the modification of the invention illustrated in Fig. 3,applicant provides a method of and a systen: for reheating cooled air byheat exchange with hot gases passing from a refrigerant com-- ment ofFig. 1 may be substituted for-the three way valve 20. As in Fig. 2, thevalve 2| is under the control of a suitable contFol instrument I5. .Thismay, for example, be a hygrostat or thermostat in the air stream, or inthe enclosure served by the conditioningisystem, or any other instrumentpositioned at any pointin the air condition-' ing system, or in theenclosure served by the system. Unde certain operating conditions thevalve 20 will ca fluid from cylinder 1 to pass to pipe H and thence tocondenser l1. However, if the relative humidity of the air in thecasingor in the enclosure is too high, or its temperature is too low, controlinstrument I! will cause valve 26 to change its position so that fluiddischarged from cylinder 1, instead of passing directly through pipes l0and II, will be routed through reheating coils 23. Since the refrigerantpassing from the cylinder Us at a relatively high temperature, it is asatisi'actory reheating medium. Fluid from heating coils 28 is returnedto the main circuit at 24 and is then passed through the condenser inthe normal. manner. Although heating coils 23, as illustrated, receivefluid from only cylinder I, it is apparent that fluid from both of thecylinders may be routed therethrough, ii desired. The passage of gasfrom the diii'erent cylinders to theheating coils may be controlled bythe same control instrument, orby diflerent control instru-' ments; andin the latter case the instruments may have the same or diflferentsettings. This system provides eflicient and elective reheating withoutany increase in the cost of operating the system, and at comparativelysmall. initial ex-.

, used in conjunction with liquid pumping systems,

gas engines and other types 01' displacement apparatus. Y i

The term compressor element" in theclaims.

shall be understood' to refer toindividual cylinders orthe like ofcompressorapumps or other displacement apparatus, and also to completeassemblages 'oi compressors,' pumps or displacement apparatus. Applicantdoes not restrict himself to compressors, MP or displacement alsopreventshigh pressure fluid from lines 0, ll apparatus of any particulartype. and these may 75 Refrigerant gas is 1 be of the reciprocating,centrifugalor any other desired type.

Since many modifications may be made in the invention without departingfrom its scope, it-ia to be understood that the above description andaccompanying drawing shall be interpreted as illustrative only, and notin a limiting sense, applicant limiting himself only as indicated intheaccompanying claims.

I claim:

1. In a refrigerating system of the character described, incombination-a plurality of compressor elements in parallel, feed meansfor supplying fluid to the elements, a plurality of discharge pipes forreceiving fluid discharged by the compressor elements, a by-pass lineconnecting the feedmeans and at least one of the discharge pipes, avalve for controlling the flow of fluid through said by-pass line, saidvalve being nor:

mally closed, means for opening said valve when- 'ever the load on saidapparatus falls below a predetermined point, and means for preventing.the flow of fluid from another of the, discharge pipes to said by-passline.

2. In a refrigerating system of the character described, in combinationa plurality of compressor elements in parallel, feed means for supply-,-ing fluid to said elements, a plurality of discharge pipes for receivingfluid discharged from said elements, and means for recirculating to saidfeed means from said discharge pipes fluid discharged from differentnumbers of said elements under different operating conditions, said 3.In a refrigerating system of the character described, a plurality ofcompressor elements connected in parallel arrangement, feed means forsupplying fluid to said elements means for receiving fluid discharged bysaid elements, and

means for recirculating through at least one of said elements fluiddischarged by at least one of said elements in response to decrease ofthe fluid pressure in said feed means below a predetermined point whiledelivering fluid discharged from at least another of the elements fromthe compressor in normal manner;

4. In a refrigerating system of the character described, a plurality ofcompressor elements connected in parallel arrangement, feed means forsupplying fluid to said elements, means for receiving fluid dischargedby said elements, means for recirculating through at least one of saidelements fluid discharged by at least one of said elements whenever thefluid temperature in said feed means falls below a predetermined point,and means for preventing recirculation through said compressor of fluiddischarged from at least another of said elements.

In a refrigerating system of the character described, in combination,compressor apparatus including a plurality of compressor elements, saidelements being connected in parallel arrangement, feed means forsupplying fluid to said apparatus, means for discharging fluid from saidelements, means for delivering fluid discharged from at least one ofsaid elements to the suction side of at least one of said elements inresponse to decrease of the load on the apparatus below a predeterminedpoint, and mean's for directly discharging from said compressorapparatus fluid discharged from at least one of said elements.

6. The combination with a refrigerating system including an evaporatorand a condenser,'of a compressor apparatus including a plurality oicompressor elements in parallel arrangement, feed means for supplyingevaporated refrigerant from said evaporator to said compressorapparatus, means for discharging fluid from said elements, means forrecirculating fluid dischaged from at least one ofsaid elements wheneverthe heat load on said evaporator falls below a predetermined point, andmeans delivering fluid discharged from at least another of said elementsdirectly to said condenser from said compressor apparatus at all timesduring operation of said compressor apparatus, saidfluid recirculatingmeans being arranged to supply fluid to at least one of saidlast-mentioned elements.

7. The combination with a refrigeratingsystem including an evaporatorand a condensenvof a compressor apparatus including a plurality ofcompressor elements connected in parallelarrrangement, feed means forsupplying evaporated refrigerant from said evaporator to said compressorapparatus; ,means for discharging compressed refrigerant fluid from saidelements,-

means for recirculating through said compressor apparatus fluiddischarged from at least one of said elements in response to decrease ofthe heat

